The following abbreviations are herewith defined, at least some of which are referred to within the following description: Third Generation Partnership Project (“3GPP”), Positive-Acknowledgment (“ACK”), Binary Phase Shift Keying (“BPSK”), Clear Channel Assessment (“CCA”), Cyclic Prefix (“CP”), Channel State Information (“CSI”), Common Search Space (“CSS”), Downlink Control Information (“DCI”), Downlink (“DL”), Downlink Pilot Time Slot (“DwPTS”), Enhanced Clear Channel Assessment (“eCCA”), Evolved Node B (“eNB”), European Telecommunications Standards Institute (“ETSI”), Frame Based Equipment (“FBE”), Frequency Division Duplex (“FDD”), Frequency Division Multiple Access (“FDMA”), Guard Period (“GP”), Hybrid Automatic Repeat Request (“HARQ”), Licensed Assisted Access (“LAA”), Load Based Equipment (“LBE”), Listen-Before-Talk (“LBT”), Long Term Evolution (“LTE”), Machine Type Communication (“MTC”), Multiple Input Multiple Output (“MIMO”), Multi User Shared Access (“MUSA”), Negative-Acknowledgment (“NACK”) or (“NAK”), Orthogonal Frequency Division Multiplexing (“OFDM”), Primary Cell (“PCell”), Physical Broadcast Channel (“PBCH”), Physical Downlink Control Channel (“PDCCH”), Physical Downlink Shared Channel (“PDSCH”), Pattern Division Multiple Access (“PDMA”), Physical Hybrid ARQ Indicator Channel (“PHICH”), Physical Random Access Channel (“PRACH”), Physical Resource Block (“PRB”), Physical Uplink Control Channel (“PUCCH”), Physical Uplink Shared Channel (“PUSCH”), Quality of Service (“QoS”), Quadrature Phase Shift Keying (“QPSK”), Radio Resource Control (“RRC”), Random Access Procedure (“RACH”), Resource Spread Multiple Access (“RSMA”), Round Trip Time (“RTT”), Receive (“RX”), Sparse Code Multiple Access (“SCMA”), Scheduling Request (“SR”), Single Carrier Frequency Division Multiple Access (“SC-FDMA”), Secondary Cell (“SCell”), Shared Channel (“SCH”), Signal-to-Interference-Plus-Noise Ratio (“SINR”), System Information Block (“SIB”), Transport Block (“TB”), Transport Block Size (“TBS”), Time-Division Duplex (“TDD”), Time Division Multiplex (“TDM”), Transmission Time Interval (“TTI”), Transmit (“TX”), Uplink Control Information (“UCI”), User Entity/Equipment (Mobile Terminal) (“UE”), Uplink (“UL”), Universal Mobile Telecommunications System (“UMTS”), Uplink Pilot Time Slot (“UpPTS”), Ultra-reliable and Low-latency Communications (“URLLC”), and Worldwide Interoperability for Microwave Access (“WiMAX”). As used herein, “HARQ-ACK” may represent collectively the Positive Acknowledge (“ACK”) and the Negative Acknowledge (“NAK”). ACK means that a TB is correctly received while NAK means a TB is erroneously received.
In certain wireless communications networks, to avoid resource collision in uplink communication, the networks adopt orthogonal multiple access (“OMA”). The networks may also use scheduling-based uplink transmission so that the orthogonal resources are assigned for different UEs. Moreover, any uplink communication (e.g., except PRACH) may be scheduled and/or controlled by an eNB. As compared to OMA, non-orthogonal multiple access (“NOMA”) may support signal superposition in an orthogonal resource. Accordingly, NOMA may enhance spectrum utilization efficiency, such as in cases of overloaded transmission. Moreover, since NOMA may separate superposed signals at the receiver by using more advanced algorithms, NOMA may support reliable and low latency grant-free transmission. Such transmission may be used for massive MTC and/or URLLC.
In some configurations, there may be no clear difference between autonomous, grant-free, and/or contention based UL transmission. In certain configurations, contention based UL transmission may include autonomous, grant-free, and/or grant-less transmission.
In configurations that use NOMA, (e.g., SCMA, MUSA/RSMA, PDMA) different UEs may be differentiated by different spare codewords, scrambling codes, and/or transmitting vectors transmitted by UEs and then combined through a channel, so that a receiver may separate the superposed signals by using advanced algorithms (e.g., message passing algorithm (“MPA”) for SCMA and PDMA, successive interference cancellation (“SIC”) for MUSA and PDMA, and matching filter (“MF”) for RSMA). Certain receiver algorithms may have better performance at the cost of more complexity. Considering that an eNB may be able to handle higher complexity than a UE, NOMA may be better for uplink transmission than downlink transmission. When NOMA is combined with UL grant-less/contention based transmission, it may support reliable and low latency UL transmission, which may be used for massive MTC and URLLC.
Nevertheless, if the grant-less UL transmission is directly introduced, it may result in problems with eNB reception due to the eNB not being aware of time-frequency resources, a modulation and coding scheme (“MCS”), HARQ process identification (“ID”), redundancy version (“RV”), and/or new data indicator (“NDI”), and so forth for a transmitting UE. Without the information of time-frequency resources, the eNB may blindly detect each possibility of resource usage. Such blind detection may result in excessive complexity and may use too much processing time. Moreover, without MCS information, an eNB may not be able to decode received data. Furthermore, without information corresponding to HARQ process ID, RV, and NDI, an eNB may not be able to differentiate whether the received data is retransmitted data, is new data, corresponds to a particular HARQ process, and/or corresponds to a particular RV.